"Windows 8 build 7850.0.winmain_win8m1.100922-1508 contains a number of references to a brand new feature in Windows: Portable Workspaces. Microsoft will allow Enterprise customers to create USB storage driven copies of Windows. 'Portable Workspace is a Windows feature that allows you to run Windows from a USB storage device', notes Microsoft in its description of the feature inside Windows 8." So, yeah, something we've been waiting for in Windows since, well, forever. Also, push notifications, a screenshot tool and a new webcam application have been discovered as well.

You can change the shell, but why would you want to change the WM? If you change the WM, you lose Remote desktop, you lose compositing, you lose pretty much everything, they way Windows is written, the WM is Windows, it can't be changed.

Why you would want to is beyond me anyway, if you want another WM, use something other than windows, the two are synonymous.